USE OF GRASSED BASINS TO FILTER RIVER WATER FOR SUBSURFACE IRRIGATION: SYSTEM DESIGN, CONSTRUCTION AND PERFORMANCE

Previous research in the St. Lawrence Lowlands, in the province of Quebec, has shown that subsurface irrigation using subsurface drainage systems, increases the yield of maize and soybean by as much as 30%. However, to reach this goal and maintain the productivity of the system, the irrigation water must be free of sediments which could block the subsurface drain pipes. This paper presents the results of research on an economical means of filtering water for subsurface irrigation. It was found that grass filter basins are very efficient in removing sediment from river water. Grass filter basins having drain pipes in trenches 300 mm wide and backfilled with sand resulted in more than 90% of sediments being removed from the river water. It was found that the filtration system need occupy less than 0.2% of the area to be irrigated. In addition, filtration rates per unit area of filter basin and per unit length of filter trench and drain pipe, were also determined. River water was also filtered in basins cove...